The “health properties” of metallic silver (that is, its antiseptic, antibacterial, antiviral, antimicrobial effects) was known for centuries before knowledge of bacteria, viruses and microbes generally even existed. In antiquity (Hippocrates of Cos and Galen of Pergamum, both physicians), and well through the Middle Ages, silver vessels were used in the care of those who were ill and wounded. For example, E. Bradford in “The Great Siege [Malta, 1565]” (New York, Harcourt, Brace & World Inc., 1961, pp. 190-191) describes the practices of the Knights of the Order of St. John, who were hospitalers, at Malta as:                “Simple though their surgery was and ignorant though they were in many ways, they did at least understand the rudiments of hygiene. In the hospital, where under normal conditions both rich and poor, Knight and commoner, were served off silver plate—to increase “the decorum of the hospital and the cleanliness of the sick”—some attempt was made, even during the siege, to look after the patients properly.” [Emphasis added. Internal quotation from Francisco Balbi de Correggio, “La verdadera relación de todo lo que el ano de MDLXV ha succedido en la Isla de Malta,’ (Barcelona, 1568)].        
It was later discovered that the actual bactericide was not the metallic silver, but the silver ions on the surface of the bulk metallic silver. Thus, the beneficial effect of using silver vessels may be attributable to the migration of silver ions from the bulk silver to the food and drink that was consumed. With the knowledge that silver ions were are actual “antiseptic,” solutions of certain silver salts (e.g. silver nitrate) that are readily soluble in water were used as an antiseptic and bactericide for many decades. Until the 1980s, dilute silver nitrate eye drops were placed in the eyes of newborns to prevent neonatal conjunctivitis, which could lead to blindness in the newborn, which may occur after birth. (This practice has generally been discontinued in favor of the use of erythromycin ointment).
Recently, the use both metallic silver particles and silver salts have been described in the patent and technical literature as a means for imparting antibacterial properties to a variety of materials such as yarns, fabrics, glass and other materials. Yahoo Lv et al. (Polymers for Advanced Technologies, Vol. 19 (1008), pages 1455-1460) have shown that silver (Ag0) nano-particles coated on a glass slide have antibacterial/antiviral properties resulting from close attachment of the nano-particles with the bacterial cells. The principle activity of silver (0) particles is due to the production of silver ions within an aqueous matrix containing the bacteria. Di Nunzio et al in WO 2006/058906 describe prosthetic devices or implants having at least a surface layer or a part thereof (that is, an element of the prosthetic device or implant) made of a glass, glass-ceramic or ceramic material containing ions exchangeable with silver ions, and subjecting the device “to a silver ion containing aqueous solution ion-exchange process,” [id at the Abstract]. Di Nunzio et al., J. European Ceramic Society Vol. 24 (2004), pages 2935-2942, discuss bioactive glasses containing silver on their surface that were produced by ion-exchange from dilute silver nitrate melts. Verne et al, J. Material Science; Materials Medicine Vol. 20 (2009), pages 733-740, present test results of the surface doping of biocompatible glass that was described in WO 2006/058906. U.S. Pat. No. 7,232,777 describes yarns and fabrics having an antimicrobial silver particulate finish.
Silver ions do not possess a single mode of action. They interact with a wide range of molecular processes within microorganisms resulting in a range of effects from inhibition of growth and loss of infectivity to cell death (cytotoxicity). The mechanism depends on both the concentration of silver ions that are present and the sensitivity of the microbial species to the silver ions. Contact time, temperature, pH and the presence of free water all impact on both the rate and extent of antimicrobial activity. However, the spectrum of activity is very wide and the development of resistance relatively low, especially in clinical situations. Silver ions are known to be effective against some 650 types of bacteria.
The prevalence of “touch screens” in contemporary society gives rise to many surfaces that can harbor microbes, bacteria and viruses, and these microbes can be transferred from person to person. The present disclosure is directed to glass surfaces and to the application of the antimicrobial properties of silver ions to glasses such as the cover glasses used on many modern devices, for example, ATMs, touch screen computers, cellphones, electronic book readers, and similar devices.